1. Field
The present invention relates generally to electronics, and more specifically to a wireless multi-antenna station.
2. Background
A multiple-input multiple-output (MIMO) communication system employs multiple (T) transmit antennas at a transmitting station and multiple (R) receive antennas at a receiving station for data transmission. A MIMO channel formed by the T transmit antennas and R receive antennas may be decomposed into S spatial channels, where S≦min {T, R}. The S spatial channels may be used to transmit data in parallel to achieve higher throughput and/or redundantly to achieve greater reliability.
A multi-antenna station is equipped with multiple antennas that may be used for data transmission and reception. Each antenna is typically associated with a transceiver that includes (1) transmit circuitry used to process a baseband output signal and generate a radio frequency (RF) output signal suitable for transmission via the antenna and (2) receive circuitry used to process an RF input signal received via the antenna and generate a baseband input signal. The multi-antenna station also has digital circuitry for processing data for transmission and reception.
The antennas of the multi-antenna station may not be located near the transceivers for various reasons. For example, it may be desirable to place the antennas at different locations and/or with sufficient separation in order to (1) decorrelate the spatial channels as much as possible and (2) achieve good reception of RF input signals and transmission of RF output signals. As another example, the multi-antenna station may be designed such that it is not possible to locate the antennas near their associated transceivers. In any case, if the antennas are not located near the transceivers, then relatively long RF cables or transmission lines are needed to connect the antennas to the transceivers. A fair amount of signal loss may result from the long connection between the antennas and the transceivers. This signal loss increases the receiver noise figure on the receive path and lowers the transmit power level on the transmit path. These effects make the system less power efficient and degrade performance.
There is therefore a need in the art for techniques to connect the antennas to the transceivers.